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Navigating the St. Lawrence: Challenging Waters, Rich History and Bright Future

11 minute read

The St. Lawrence marine corridor plays a key role in Canada’s economy and supply chain. The geography as well as the unique physical attributes and water dynamics of the St. Lawrence challenge the commercial ships transiting through this maritime route in more than one way.

The St. Lawrence River is one of the world’s major rivers, flowing into the estuary and gulf that shares the same name. It provides nearly 1,200 kilometres of navigable waters that link the Great Lakes and the heart of North America to the Atlantic Ocean, acting as a vital artery for Canada’s economy and supply chain.

Some 8,000 commercial vessels sail this marine highway every year, carrying more than 100 million tonnes1 of cargo. In 2017, marine shipping activities on the St. Lawrence Seaway contributed more than $16 billion to the Canadian economy, according to a study conducted by the Chamber of Marine Commerce.

The St. Lawrence marine corridor, which is made up of the river and the Seaway, is recognized for its economic value including its strategic location for trade with the United States, Europe and the world. Its challenging physical features and dynamic waters make it one of the most complex waterways in the world for ships to navigate. It is part of the traditional territory of the Kanien’keha:ka (Mohawk) Nation and the Wabanaki peoples including the Wolastoqiyik (Maliseet) Nation.

This blog explores the physical characteristics of the St. Lawrence and the main challenges they pose to the commercial vessels using the waterway. It also gives an overview of the safety measures in place and the various initiatives aimed at enhancing the productivity and sustainability of marine shipping on this major route.

The St. Lawrence Seaway: A Short History

Commercial marine shipping on the St. Lawrence corridor has a long history. Indigneous people paddled the waters they called Kaniatarowanenneh, or the “big waterway”, more than 9,000 years ago using it as a trading and transportation route. Learn more about the major role Mohawks have played in the history of the St. Lawrence and their involvement in the protection and preservation of ecosystems along the St. Lawrence here.

The European explorers who settled New France, Upper and Lower Canada used the St. Lawrence as an important transportation link. As North America grew and prospered, major development of the St. Lawrence River was required to allow commercial vessels to sail between Montreal and the Great Lakes. During the 1930s and 1950s, development activity included dredging2, digging channels, and the construction of locks. In the 1950s, the decision was taken by Canada and the United States to jointly build the St. Lawrence Seaway. When it opened in 1959, it was considered one of the great engineering feats and examples of international co-operation of the 20th century.

Covering a distance of 306 km, it links Montreal with Port Colborne, Ont., on Lake Erie and includes 15 locks – seven of which are located in the St. Lawrence (five on the Canadian side and two on the American side) – allowing ships to transit through it despite an elevation gain of 168 metres. From there, it reaches Lake Superior and Thunder Bay, the gateway to Canada’s grain producing Prairies, some 183 metres above sea level. The St. Lawrence Seaway is jointly managed by Canada and the United States, to ensure that it remains safe and well maintained.

Navigating Safely: The St. Lawrence Pilots

Under Canada’s Pilotage Act, the St. Lawrence between Les Escoumins – located on Quebec’s North Shore – and Montreal, the St. Lawrence Seaway and the Great Lakes are mandatory pilotage areas. In these areas of higher risk, ships of certain sizes and tonnages are legally required to have one or more licensed pilots on board. These pilots have in-depth knowledge of the river, its dynamics, and the regulations and restrictions in force in their pilotage area. They ensure that ship transits are safe, efficient and respect sensitive ecosystems.

Between Les Escoumins and Montreal, foreign vessels over 35 metres in length, Canadian vessels over 70 metres in length whose total transport capacity (gross tonnage) exceeds a certain tonnage, and barges carrying pollutants are subject to compulsory pilotage. The Laurentian Pilotage Authority is the Crown corporation responsible for managing compulsory pilotage on this section of the St. Lawrence as well as on the Saguenay River. It is responsible for assigning licensed pilots to the ships that require them.

The Authority works with the Corporation of the Lower St. Lawrence Pilots, for transits between Les Escoumins and the Port of Quebec or towards Saguenay, and the Corporation of Mid St. Lawrence Pilots for transits between the ports of Quebec and Montreal. On the St. Lawrence Seaway – from the entrance of the Saint-Lambert lock to Lake Ontario – as well as on the Canadian waters of the Great Lakes, foreign ships over 35 metres in length, those with gross tonnage exceeding 1,500 tonnes and certain tugs are subject to compulsory pilotage. The Great Lakes Pilotage Authority manages and assigns licensed pilots in this area.

A Complex Route with Multiple Challenges

With its shallows, fogs, the presence of ice in winter, strong tides, multi-directional currents, and locks, the St. Lawrence is not a long, calm river. Its physical attributes and the dynamics of its waters pose many challenges to navigation and logistics.

Click image to expand:

Map of St. Lawrence Corridor

Varying Widths and Depths

Since the St. Lawrence spans a gulf, an estuary and a river, its width and depth fluctuate considerably from one section to another. More than 300 km wide in the Gulf of St. Lawrence3, it gradually narrows in the estuary and the river where, in places, it is only one kilometre wide4. In comparison, the Strait of Juan de Fuca – which connects the Salish Sea to the Pacific Ocean on the west coast of Canada – is about 10 kilometres wide at its narrowest point. The depth of the St. Lawrence also fluctuates from one sector to another depending on bottom topography and the tides which cause the water levels to vary. In the gulf and the estuary, for example, the St. Lawrence is several hundred metres deep while the depth of the river is just over a dozen metres.

The shipping channel – the designated corridor through which ships transit – also has varying dimensions5 depending on the area. Between Les Escoumins and Montreal, the minimum width of the channel varies from 229 metres to 305 metres and its depth ranges from 10.7 metres to 12.5 metres. Between Trois-Rivières and Montreal the width of the channel is the narrowest (229 metres), and the section between Quebec and Trois-Rivières is where the channel is the shallowest (10.7 metres). However, in this segment, ships can benefit from tides and available depths that exceed 10.7 metres at certain times of day.

Access to the Seaway: A Matter of Size

The narrowness of the river, its shallows, as well as the presence of locks in the Seaway impose constraints – width and draft6 – to the ships that transit the river. Ships coming from the lower St. Lawrence whose length and beam do not exceed 294 metres and 44 metres, can reach Montreal. Between Les Escoumins and the Port of Montreal, the maximum draft allowed to ensure safe transits despite the shallows varies according to the tides and available water levels. Between Montreal and Lake Erie, due to the size of the locks, only vessels whose length and beam does not exceed 225.5 metres and 23.8 metres7 can access the Seaway. The maximum draft allowed for ships transiting through the St. Lawrence Seaway varies between 8 and 8.08 metres8, depending on water levels.

How Ships Approach and Overtake Each Other

When ships meet on the St. Lawrence and seek to pass each other, strict rules are in place that are governed by the size of the vessels in transit and the dimensions and layout of the shipping channel. To ensure safe management of the marine traffic in the sections where there are many topographical constraints, pilots refer to the navigation chart VN301. This chart highlights the sections of the St. Lawrence in which ships can or can’t meet and overtake each other based on their size. For example, between Quebec and Cap Ste-Michel à l’Île aux Vaches in Montérégie, vessels from 270 to 300 metres length can’t meet or overtake one another in more than ten locations.

How the Seasons Affect Navigation

Marine shipping activities and navigation on the St. Lawrence are seriously influenced by seasonal changes and weather conditions. In the winter, precipitation, the presence of ice in the shipping lanes and the absence of illuminated buoys9 downstream from Montreal add a degree of complexity to ship movements. To ensure that shipping activities remain unhampered and safe in these situations, the Canadian Coast Guard is setting up an Ice Operations Centre which provides pilots with information on ice conditions, de-icing activities and safe routes to follow. Moreover, during winter, the Laurentian Pilotage Authority mandates that two licensed pilots must be on board ships transiting between Les Escoumins and Montreal. Meanwhile, the St. Lawrence Seaway is closed to navigation from the end of December to mid-March, since the ice makes the lock system impassable.

Photo credit: Laurentian Pilotage Authority

In the spring, melting ice and occasional heavy precipitation raise water levels in the St. Lawrence and the Great Lakes. High water levels can have significant economic effects for the marine shipping industry and waterfront communities. Ships in motion create wakes; when water levels are high, this added turbulance can flood or damage shorelines and riverside infrastructure. To reduce these risks and ensure that vessel transits remain safe when water levels are above normal, various measures can be implemented by the pilotage authorities and the St. Lawrence Seaway Management Corporation, including:

  • delaying the opening of the commercial shipping season on the St. Lawrence Seaway;
  • tightening speed limits and maximum draft permitted;
  • reducing the number of ships in the shipping lanes;
  • prohibiting certain vessels from transiting at night – for example, wide beam vessels (more than 32.5 metres wide) and very long vessels (more than 270 metres long)10;

High water levels are a major seasonal issue as they can cause significant damage along the river as well as delay the movement of goods and cut commercial productivity.

Finally, in the summer, the warm air masses that travel over the cold waters of the St. Lawrence create considerable temperature differences on the water’s surface, which generate fog and reduce visibility in the shipping lanes.

Photo credit: Corporation of the Lower St. Lawrence Pilots

Tides and Currents

From the Gulf to Trois-Rivières, the St. Lawrence is influenced by strong tides and currents that cause significant variations in water levels. The safe passage of ships – especially large ocean-going vessels – in this part of the river is dependent on the tides. For pilots, it’s a matter of synchronization: they must use the tides and currents to create optimal windows for passage and assure ships have sufficient depths. A ship arriving at Les Escoumins during a rising tide could benefit from favourable water levels and resulting effects throughout its journey to an upstream port. Conversely, a large vessel entering the St. Lawrence during an ebb tide may have to slow down and even drop anchor, to wait for the tide to turn before it can continue on its course.

Optimization of Transits on the St. Lawrence: Towards a Digital Waterway

The St. Lawrence is a busy marine corridor. The number of ships and the volume of goods passing through it continue to grow every year. Therefore, the optimization of ship transits is and will remain a key element to ensure safe, efficient and sustainable marine shipping activities on this route.

Vessels that move from point A to B without being interrupted, that benefit from favourable tides and helpful currents, and whose arrival at the port is timed with the dock availability, consume less fuel and emit fewer pollutants – greenhouse gases, sulphur oxides and others. Smooth transits that allow cargoes to be delivered more quickly and efficiently have a positive impact on the productivity and environmental performance of the entire supply chain.

The modernization of the ways of doing things plays an important role in transit optimization on the Laurentian route. The “digitization” of the St. Lawrence to make it a smart marine corridor is also an integral part of Quebec’s maritime vision (in French only), which aims to place artificial intelligence and automation at the forefront to boost the efficiency of commercial marine shipping and stimulate sustainable economic development on the river.

Industry stakeholders – ports, pilots, St. Lawrence Seaway Management Corporation, and maritime innovation research centres – have already begun this digital shift through various initiatives. Among them, the implementation of an automated hands-free mooring system in all the locks of the St. Lawrence Seaway; the creation of a tidal current optimization software; and the development of a travel optimization software that calculates, in just a few seconds, the best routes to prevent operational delays caused by weather conditions, currents, navigation restrictions, etc. Recently, the Laurentian Pilotage Authority has started working on a software application to optimize the pilotage and passage of ships between Les Escoumins and Montreal. Developed jointly with Innovation Maritime – the applied research centre affiliated with the Institut maritime du Québec (Quebec’s Maritime Institute) – this application will allow the Authority to automate and optimize transit planning in real time based on weather data, water levels at different times of the day, vessel size, and more. This project should be completed in 2022.

All of these initiatives will contribute to improving the safety of shipping on the St. Lawrence, the smooth and efficient flow of maritime traffic as well as protect the river environment.

Learn more

Economic impact of marine shipping in Canada

Maritime innovation projects on the St. Lawrence

St. Lawrence Seaway

Marine pilotage in Canada

Features of Marine Transportation in the St. Lawrence

#marinesafety #sustainablemarineshipping #pilotage

1 St. Lawrence 2011-2026 Action Plan. (2017). Navigation on the St. Lawrence Echo of the Past, Path to the Future. Government of Quebec. p.7

2 Dredging is a clearing operation that involves scraping the bottom of a water body to remove natural obstacles such as rocks and sediments. Dredging ensures that marine corridors such as the St. Lawrence River are free of any obstacles that could compromise the flow and safety of the vessels passing through it.

3 Stratégies Saint-Laurent. (2011). Le Saint-Laurent – Géographie. (Available in French only).

4 Stratégies Saint-Laurent. (2011). Le Saint-Laurent – Géographie. (Available in French only).

5 Data on widths and depths of the shipping channel between Les Escoumins and Montreal provided by the Laurentian Pilotage Authority (2020).

6 Draft corresponds to the submerged part of a ship’s hull; the height of the draft varies according to the load carried. The more a ship is loaded, the greater the height of the submerged part (draft).

7 St. Lawrence Seaway Management Corporation. (2020). Locks, Canals & Channels. Retrieved May 27, 2020.

8 St. Lawrence Seaway Management Corporation. (2020). Seaway Notice No. °1 – 2020. Retrieved May 27, 2020.

9 In winter, illuminated buoys are replaced by smaller non-illuminated buoys designed to resist ice floes. However, during winter 2019-2020, 32 new lighted, four-season buoys were tested by the Canadian Coast Guard between Les Escoumins and Montreal. These new buoys will eventually replace the current buoys and provide ships with visual markers all year round.

10 Fisheries and Oceans Canada. (2020). Notices to Mariners 1 To 46 Annual Edition 2020. 27A – Guidelines for the Transit of Wide Beam Vessels and Long Vessels. p. 204.

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